A ship lifting device is known from U.S. Pat. specification No. 4,381,723 comprising a deck with a downwardly open lifting skirt positioned below the platform and provided with valves for controlling the buoyancy of the deck when air is supplied and removed from the liftingskirt. The air is supplied from the bottom flowing through discharge valves located along the bottom of the basin. The deck with associated lifting skirt is pivotally connected with stationary foundations by means of a parallelogram linkage system. This shiplifting device is encumbered with the drawback that it is not possible to control sufficiently exactly the upward and downward movements of the deck.